/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var sumNumbers = function (root) {

  return getData(root, root.val)
  function getData(node, data) {
    if (node.left) {
      getData(node.left, '' + data + node.left.val)
    }
    if (node.right) {
      getData(node.right, '' + data + node.right.val)
    }

    return data
  }
};